About the thigh prosthesis
Thigh prosthesis, a prosthesis for thigh amputation, is suitable for amputees from 10cm under the ischial tubercle to 8cm above the knee joint space.
The Prosthetics Knee joint is divided into two stages, one is the swing period, which is the process of the artificial leg swinging backward from the ground and then forward; the other is the support period, which is the process from the heel landing of the artificial leg to the toe off the ground. First of all, in the swing period, the functions of air pressure and hydraulic pressure are to control the backward speed and forward speed, both of which can be adjusted, and the other is to control the height of the heel raised when swinging backward. There is also a small role, which is to control the knee joint not to make a "click" sound when the prosthesis is is fully extended. In fact, this role is not very big. Most of the knee joints finally rely on the cushion to solve this problem. Every joint is different. The difference between the intelligent prosthesis and the common prosthesis is that there is a sensor for sensing, and then it is transmitted to a chip for control. Cleg's advantage is actually its hydraulic control system, a very special piston, which controls six hydraulic circuits at the same time. The design is very exquisite and saves a lot of electricity. Ossur's electromagnetic legs are controlled by "magnetorheological" materials. The most advanced technology lies in the use of new materials.
2. There is no good or bad function of each knee joint in the thigh prosthesis. Of course, the quality is different. The function depends on two aspects: structure and control mode. The problem of simple structure and poor stability of the uniaxial knee joint can also be solved by load-bearing self-locking function. Generally speaking, it is a kind of joint with strong adaptability, which can be used by even the weak people, amputees of both legs and the elderly - of course, the elderly prefer the uniaxial knee joint with lock. The structure of the four-bar knee joint is a little more complicated, but it is the closest to the human knee joint in terms of bionics. The stability is good, in fact, the flexibility can also be compensated by the adjustment of the prosthesis to the line.
(1) Traditional thigh prosthesis: according to the main materials, it can be divided into aluminum thigh and wood thigh. The internal receiving cavity of the residual limb of the aluminum thigh prosthesis is is made of leather, the bottom of the receiving cavity is open, the thigh part and the calf part of the prosthesis are made of thin aluminum plate; the knee and ankle joints are uniaxial joints, and the knee joints are divided into two types: with lock and without lock; the artificial feet are mostly made of rubber, and the prosthesis is is suspended by the waist sling or the metal hinge belt of the hip.
This kind of prosthesis is suitable for thigh amputees of various stump lengths, and is cheap. The disadvantage is that the weight is heavy, so it is difficult to achieve a good bearing of ischial tubercle (two ischial tubercles can bear even weight in normal sitting position), and it is easy to cause skin pain inside the thigh root.
(2) Modern thigh prostheses:
① The socket of the stump is made of glass fiber, carbon fiber reinforced resin or some thermoplastics according to the plaster model of the amputee's stump, which can easily achieve good bearing of ischial tubercle and full contact with the stump.
The bottom of the receiving cavity is provided with a valve for one-way ventilation. When the prosthesis is loaded, the air at the end of the stump is squeezed and eliminated. When the prosthesis is lifted, the prosthesis is sucked on the stump, so it is called suction thigh prosthesis. If the stump is too short and the soft tissue is too little, the suction type thigh can not be used, and a waist sling or a hip hinge belt is needed to suspend the prosthesis. ② Knee joint: it has more varieties and functions than traditional prosthesis, and it is better.
Common varieties are: a knee joint with hand lock: locked during walking, straight leg walking, open when sitting, suitable for the elderly, weak and short disabled. B. knee hinge with load-bearing self-locking structure: during each step of walking, the knee joint of the prosthesis will be locked automatically to ensure that the knee joint will not bend suddenly (commonly known as soft legs). When walking, the lock will be opened automatically and the knee can be bent, so the walking appearance is more natural.
C pneumatic knee joint, hydraulic knee joint: each step of this kind of knee joint can not only ensure that the prosthesis does not break soft legs when bearing weight, but also can walk slowly if you want to walk slowly, or walk quickly if you want to. This performance is called "step frequency following", which is the characteristic of pneumatic knee joint and hydraulic lacquer joint. The disadvantage is that this kind of knee joint is heavy and expensive. ③ The thighs and calves are mostly of skeletal structure, covered with plastic sponge and covered with skin color hosiery. They have good appearance and are not easy to break the pants.
④ At present, most of the amputees in China choose the single axis prosthesis, which is beneficial to adjust the alignment of the prosthesis and ensure the stability of the knee joint.